Wet System Control Valve

Wet valve
sprinkler systems are permanently charge with water and are designed to actuate
operate electric, and/or hydraulic alarms when there is a steady flow of water
into the system that is equivalent to the discharge rate of one or more
sprinklers.

When the
fire system is initially being pressurised, water will flow into the system
until the water supply and system pressure become equalised, and the torsion
spring closes the clapper in the Alarm Check Valve and forms a seal. This
seal prevents any water flow through the alarm port to the alarm devices.

In the event
of a fire, the steady flow of water equivalent to the discharge rate of one or
more sprinklers will cause a pressure imbalance on the Alarm Check Valve seal.
This causes the clapper to open, to allow a continued flow of water through the
sprinkler system until the fire has been extinguished and the Wet system
control valve has been closed and reset in readiness for further emergencies.